ON THIS day 25 years ago: a resounding vote of confidence in the territory's economic future had been recorded by industrialists, according to a survey conducted by the Federation of Hongkong Industries. Of 25 major factories surveyed, 24 had indicated they were continuing with their plans for expansion which would cost many millions of dollars. The federation's chairman, Dr S. Y. Chung, said: ''This is a very good indication of the continuing confidence of industrialists in the economic future of Hongkong''. ''It also shows that industrialists are quite willing to put money into Hongkong.'' The group's director, Mr Y. H. Chen, said the survey had been carried out because the federation wanted ''an idea of future advancement of industries''. The factories involved in the survey were all ''quite large'' and comprised textile, plastics, metal and food industries. MIDDLE-aged people were the worst offenders in spitting in public, according to a spokesman for the Urban Services Department. During a month-long anti-spitting campaign, a total of 989 people were warned - 609 aged between 30 and 50, 102 over 50 and 278 under 30. Commenting on the campaign, the spokesman said the results were promising. ''The main object has been to put across the idea to the citizens of Hongkong that spitting in public is an anti-social, disgusting and dangerous habit,'' he said. The spokesman said that although the Urban Council had a responsibility to do everything possible to eradicate spitting, much better results would be obtained if community leaders and school teachers convinced young people and children to refrain from spitting.